Vortex Tube

Abstract

A vortex tube allowing for control of the velocities, flow, and pressure differentials otherwise present in a free vortex like that found in a tornado is disclosed. The presently disclosed vortex tube may be used for the control and implementation of the otherwise chaotic aspects of a true tornado and vortex (i.e., with less energy and a narrowed and more focused and intense vortex) when implementing the critical flow regime in a fluid flow system.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the priority benefit of U.S. provisional application No. 61/165,911 filed Apr. 2, 2009 and entitled “Vortex Tube,” the disclosure of which is incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to fluid dynamics. The present invention more specifically relates to the creation and management of vortex flows, which may be implemented as a separator or ejector in a fluid flow control system.

2. Description of the Related Art

Industry generally requires the movement of fluid flow for any number of reasons and as might be related to any number of different applications. One example is in the context of air conditioning whereby heat energy is moved into or out of an enclosed space by means of a body of air. Another example includes water heating whereby heat energy is applied to a body of water in order to raise its temperature. Both fluid control systems—air and water—may be measured using a coefficient of performance (COP) reflective of a ratio of the energy gained by the body of air or liquid with respect to the input energy. Many prior art air conditioning systems operate at a COP ratio between 2 and 3.5 whereas liquid heating systems tend to operate at a COP closer to 1. Both COP ratios are generally viewed as inefficient, but an inherent limitation of fluid flow control that corresponds directly to a compressor component in the fluid flow control system.

FIG. 1 illustrates such a prior art system 100 including a compressor 110 component as referenced above. The system 100 of FIG. 1 also includes a condenser 120, expansion valve 130, and evaporator 140. The system 100 of FIG. 1 might correspond to a vapor compression system whereby the compressor 110 compresses a gas to approximately 238 pounds per square inch (PSI) and a corresponding temperature of 190 F. The condenser 120 might then liquefy the heated and compressed has to 220 PSI and 117 F. The now liquefied has may be passed through expansion valve 130 where the pressure drops to 20 PSI and 34 F. The resulting refrigerant may be boiled at evaporator 140 to produce a low temperature vapor of approximately 39 F and 20 PSI. This cycle is sometimes referred to as the vapor compressor cycle and generally results in a COP of between 2.4 and 3.5, which corresponds to the evaporator cooling power capacity divided by the compressor power.

The COP of system 100 is far below that of system potential. To compress a gas in a system like that illustrated in FIG. 1 generally requires 1.75-2.5 kilowatts for every 5 kilowatts of cooling power. This sub-standard performance may be directly attributable to the underperformance of the compressor 110. There is, therefore, a need in the art for increased performance in a fluid flow control system and that obviates the inherent limitations of compressor components in such a system.

SUMMARY OF THE CLAIMED INVENTION

A vortex tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a prior art system including a compressor component.

FIG. 2A illustrates the pressure profile of a tornado.

FIG. 2B illustrates the velocity profile of a tornado.

FIG. 3 illustrates a vortex tube.

FIGS. 4A and 4B illustrate simulated velocity profiles from a vortex tube.

FIG. 5 illustrates a simulated pressure profile from a vortex tube.

FIG. 6 illustrates an alternative embodiment of a vortex tube, and which includes a spherical plug allowing for converging diverging vortex flow.

FIG. 7 illustrates velocity data for the vortex tube of FIG. 6.

FIG. 8 illustrates pressure data for the vortex tube of FIG. 6.

DETAILED DESCRIPTION

A tornado is a violent, rotating column of air. While tornadoes vary in shape and size, they typically form a visible condensation funnel. The tornado proper, however, refers to the vortex of wind—not the condensation funnel or ‘cloud.’ The central core of a tornado is calm with low pressure whereby fluid flow is slowly introduced from outside the vortex and into the rotating flow. Immediately outside a tornado, however, are very high velocities and intense fluid motion; velocity decreases with an increase in radius. The highest velocity trends close to the central core of the tornado and slowly decreases as the point of measurement moves to the outside in accordance with Bernoulli's Principle. The intensification of fluid motion in a tornado is a result of the ‘stretching’ of rotating fluid, which may occur through acceleration. The result is increased vortex motion. FIGS. 2A and 2B illustrate the pressure and velocity profile of a tornado, respectively.

The vortex of wind (i.e., the tornado) is a spinning flow of fluid; the spiral motion and closed streamlines make said motion vortex flow or motion having vorticity. Vorticity is a mathematical concept related to the amount of ‘circulation’ or ‘rotation’ in a fluid. The vorticity is the circulation per unit area at a point in the flow field and is a vector quantity whose direction is substantially along the axis of the swirl. The movement of a fluid might also be characterized as vortical if the fluid moves around in a circle, or in a helix, or if it tends to spin around some axis (i.e., solenoidal). Mathematically, vorticity ({right arrow over (ω)}) is defined as the curl of the fluid velocity ({right arrow over (υ)}):

{right arrow over (ω)}=∇×{right arrow over (υ)}.

The core of a vortex can be considered to contain a vortex line; particles in the vortex can be considered to circulate around that line. Vortex lines can start and end at the boundary of a fluid or form closed loops, but cannot start or end in the fluid in accordance with Helmholtz's theorems. Vortices will, however, readily deflect and attach themselves to a solid surface.

The circular motion of the fluid in vortices contains energy. As fluids exhibit viscosity, the energy is slowly dissipated from the core of the vortex. Such is the case in a Rankine vortex, which describes the velocity profile of a vortex in a real, viscous fluid. Through viscosity driven dissipation of a vortex, a vortex line may end in a fluid rather than merely at the boundary of a fluid. The characteristics of a tornado or vortex may be captured and implemented in the context of a vortex tube 300 like that illustrated in FIG. 3.

The vortex tube 300 of FIG. 3 may be utilized to instantiate cavitation or other forms of turbulence. Turbulence and cavitation are generally viewed in fluid dynamics as wasted energy. The shock waves generated as a result of turbulence and cavitation in the context of the present invention, however, might be utilized in a fluid circulation system like that disclosed in co-pending U.S. patent application Ser. No. 12/732,171 for a “Supersonic Cooling System,” the disclosure of which is incorporated herein by reference. A system like that disclosed in the aforementioned application utilizes a compression wave and operates in the critical flow regime. The shock waves generated by the presently disclosed vortex tube 300 may be used to promulgate said wave.

It should be noted that while velocity of flow is generally low at the center of a vortex tube, said velocity increases along the sides of the tube indicating a solid-like rotating flow. The pressure differences in the controlled environment of a vortex tube, too, are smaller as compared to the free vortex of a tornado. The flow patterns also vary slightly from those of a true tornado. Thus, embodiments of the presently disclosed vortex tube allow for control and implementation of the otherwise chaotic aspects of a true tornado and vortex (i.e., with less energy and a narrowed and more focused and intense vortex).

Vortex tube 300 display an overall converging-diverging structure, but specifically includes an inlet portion 310, throat portion 320, expansion portion 330, and outlet portion 340. Fluid pathway 350 runs the length of the vortex tube 300. The inlet portion 310 receives a fluid, usually under pressure, and is directed into throat portion 320 by way of convergence portion 360, which may instantiate vortex related flow behavior. The throat portion 320 provides a duct, which maintains vortex behavior, and through which the fluid is forced. The expansion portion 330 provides an expanding tube-like member wherein the diameter of the fluid pathway 350 progressively increases between the throat portion 320 and the outlet portion 340. The actual profile of the expansion portion 340 may vary dependent upon a particular fluid introduced through the tube 300 and a corresponding fluid flow system.

When a fluid enters the vortex tube 300, the throat portion 320 causes the fluid to accelerate to a high speed. The acceleration of the fluid causes a sudden drop in pressure, which results in cavitation at approximately the boundary between the funnel-like and vortex inducing convergence portion 360 and inlet portion 310 and the entry to the throat portion 320, but also being triggered along the wall of the throat portion 320. Cavitation results in a multi-phase fluid and the temperature falls as a result. The reduction in pressure, together with the multiphase fluid results in the lowering of the speed of sound with the result that fluid exits the throat portion 320 at a supersonic speed. Within the expansion portion 330, the fluid pressure remains low and the fluid expands, which causes even further acceleration.

FIGS. 4A and 4B illustrate simulated velocity profiles from a vortex tube like that of FIG. 3. A free vortex should see high velocities towards the centre along with low pressures. In a vortex tube, the high velocity occurs near the walls, which is similar to a solid body rotation. The pressure difference between the central core and the outside stays well above the outlet pressure. FIG. 5, in turn, illustrates a pressure profile of a vortex tube like that of FIG. 3, which illustrates the pressure at the center of the vortex tube.

An alternative embodiment of a vortex tube 600 is illustrated in the context of FIG. 6, which allows for converging diverging vortex flow. The vortex tube of FIG. 6 includes a spherical plug at the core of the converging entrance. As a result of introducing the aforementioned plug insert, the fluid flow stays ‘attached’ to the central plug and does not move towards the walls as in a vortex tube like that in FIG. 3 (see FIG. 7). Higher and lower pressures result closer to the wall as is the case in a tornado. Immediately after the plug, however, the flow separates and finds its way to the outer tube while concurrently displaying a long, narrow ‘throat.’ FIG. 8 illustrates substantially lower pressures at or near the center of vortex tube 600, especially near the tip of the insert.

The size of the vortex may be controlled through the use of suction. For example, if a small amount of suction is introduced into the central tube attached to the insert, the vortex is ‘sucked in.’ As a result, the vortex may be shrunk with the higher velocity point moving ‘further in.’ Other variations in vortex tube design may be taken into consideration with respect to control of pressure and velocity of fluid flow. For example, if the walls are allowed to expand immediately after the throat, the fluid flow expands along the wall. Pressure may be controlled as a result.

While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. The descriptions are not intended to limit the scope of the invention to the particular forms set forth herein. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments. It should be understood that the above description is illustrative and not restrictive. To the contrary, the present descriptions are intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims and otherwise appreciated by one of ordinary skill in the art. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.

Claims

1. A vortex tube.